Why VPN Security Should Be Every Enterprise’s Top Priority: Lessons from the Mino Kogyo Ransomware Attack
Why VPN Security Should Be Every Enterprise’s Top Priority: Lessons from the Mino Kogyo Ransomware Attack
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Why VPN Security Should Be Every Enterprise’s Top Priority: Lessons from the Mino Kogyo Ransomware Attack
Introduction
In today’s interconnected business environment, Virtual Private Networks (VPNs) have become the gateway to corporate resources for remote workers and partners.
However, this critical access point has also become the primary target for cybercriminals.
The recent ransomware attack on Mino Kogyo, a Japanese aluminum die-casting manufacturer, serves as a stark reminder that VPN security is not just an IT concern—it’s a business survival imperative.
The Mino Kogyo Incident: A Case Study in VPN Vulnerability
On October 1, 2025, Mino Kogyo fell victim to a devastating ransomware attack that demonstrates the catastrophic consequences of inadequate VPN security. The timeline of events reveals a frighteningly efficient attack:
- 19:31 – Attackers gained initial access through compromised employee VPN credentials using stolen IDs and passwords.
- 20:32 – Within just one hour, attackers escalated privileges to obtain system administrator rights.
- October 1-4 – Over approximately three days, attackers explored the network, exfiltrated data from client devices, and remained undetected.
- October 3, 20:58 – Attackers executed system destruction, file encryption, and server initialization.
- October 4, 02:25 – The company finally detected the cyberattack—nearly three days after the initial breach.
The damage was extensive: approximately 300GB of data was exfiltrated, ransom demands were made, and the company was forced to completely shut down all VPN access points with no immediate plans for reopening them.
Anatomy of a Ransomware Attack: The Askul and Asahi Cyber Incidents In Japan
Why VPN Security Deserves Top Priority
1. VPNs Are the Front Door to Your Network
Unlike other security vulnerabilities that require multiple steps to exploit, a compromised VPN provides direct access to internal networks. In the Mino Kogyo case, attackers didn’t need to bypass firewalls, exploit zero-day vulnerabilities, or conduct sophisticated social engineering campaigns. A single set of stolen credentials gave them legitimate entry.
2. Rapid Privilege Escalation
The Mino Kogyo incident demonstrates how quickly attackers can move from initial access to complete control. In just 61 minutes, they escalated from an employee account to system administrator privileges. This “breakout time” leaves virtually no window for detection or response, making prevention through strong VPN security absolutely critical.
3. Extended Dwell Time Equals Greater Damage
Once inside through the VPN, attackers had nearly three days of undetected access. During this time, they:
- Mapped the entire network
- Identified valuable data
- Exfiltrated 300GB of information
- Prepared ransomware deployment
- Established persistence mechanisms
The longer attackers remain undetected, the more catastrophic the damage becomes.
4. Business Continuity at Stake
Following the attack, Mino Kogyo had to completely shut down all VPN access with no timeline for restoration. For modern businesses that rely on remote work and partner connectivity, this represents a crippling blow to operations. The cost extends far beyond the ransom demand to include:
- Lost productivity
- Disrupted supply chains
- Damaged customer relationships
- Regulatory penalties
- Reputational harm
How to Strengthen VPN Security: A Comprehensive Approach
Learning from incidents like Mino Kogyo’s, enterprises must implement multi-layered VPN security measures:
1. Implement Multi-Factor Authentication (MFA)
Why it matters: Even if credentials are compromised, MFA adds a critical second barrier.
Best practices:
- Require MFA for all VPN connections without exception
- Use hardware tokens or biometric authentication rather than SMS-based codes
- Implement adaptive MFA that increases requirements based on risk factors (location, device, time)
- Regularly audit MFA enrollment to ensure 100% compliance
2. Adopt Zero Trust Architecture
Why it matters: Traditional VPN models grant broad network access once authenticated. Zero Trust assumes breach and continuously verifies.
Best practices:
- Implement micro-segmentation to limit lateral movement
- Grant least-privilege access based on role and need
- Continuously authenticate and authorize every connection
- Monitor and log all VPN sessions in real-time
3. Deploy Endpoint Detection and Response (EDR)
Why it matters: Mino Kogyo implemented EDR only after the attack. Proactive deployment enables rapid detection.
Best practices:
- Install EDR on all devices with VPN access
- Configure behavioral analysis to detect anomalous activities
- Establish automated response protocols for suspicious behavior
- Integrate EDR with VPN access controls for automatic session termination
EPP vs EDR: Understanding Critical Endpoint Security Measures
4. Strengthen Credential Management
Why it matters: The Mino Kogyo breach began with compromised credentials—the most common attack vector.
Best practices:
- Enforce strong, unique passwords with minimum complexity requirements
- Implement regular mandatory password changes (every 60-90 days)
- Monitor for compromised credentials on the dark web
- Disable inactive accounts immediately
- Use privileged access management (PAM) for administrator credentials
- Consider passwordless authentication where possible
5. Network Segmentation and Access Controls
Why it matters: Limiting what VPN users can access reduces the blast radius of a compromise.
Best practices:
- Segment networks based on data sensitivity and user roles
- Implement role-based access control (RBAC)
- Regularly review and update access permissions
- Use software-defined perimeters (SDP) to hide resources until authentication
6. Continuous Monitoring and Threat Detection
Why it matters: Mino Kogyo didn’t detect the intrusion for three days. Earlier detection could have minimized damage.
Best practices:
- Implement Security Information and Event Management (SIEM) systems
- Monitor for unusual login patterns (time, location, frequency)
- Detect rapid privilege escalation attempts
- Alert on abnormal data transfer volumes
- Establish a Security Operations Center (SOC) for 24/7 monitoring
- Use User and Entity Behavior Analytics (UEBA) to identify insider threats
7. Regular Security Audits and Penetration Testing
Why it matters: Proactively identify vulnerabilities before attackers do.
Best practices:
- Conduct quarterly VPN security assessments
- Perform annual penetration testing specifically targeting VPN infrastructure
- Review VPN logs regularly for suspicious activities
- Validate that security controls are functioning as intended
- Test incident response procedures through tabletop exercises
8. Patch Management and Vulnerability Remediation
Why it matters: Outdated VPN software contains known vulnerabilities that attackers actively exploit.
Best practices:
- Maintain an inventory of all VPN infrastructure
- Subscribe to security advisories from VPN vendors
- Apply critical security patches within 48 hours
- Establish a regular patching schedule for all updates
- Test patches in a staging environment before production deployment
9. Employee Training and Awareness
Why it matters: Human error remains the weakest link in security chains.
Best practices:
- Conduct quarterly security awareness training
- Simulate phishing attacks to test employee vigilance
- Educate staff about credential protection
- Establish clear protocols for reporting suspicious activities
- Create a security-conscious culture through leadership commitment
10. Incident Response Planning
Why it matters: When prevention fails, rapid response minimizes damage.
Best practices:
- Develop and document VPN-specific incident response procedures
- Establish clear escalation paths and communication protocols
- Practice incident response through regular drills
- Maintain offline backups that can’t be accessed through the VPN
- Establish relationships with forensic investigators before an incident occurs
Beyond VPN: Complementary Security Measures
While VPN security is paramount, it should be part of a comprehensive security strategy:
- Network Access Control (NAC): Verify device health before granting VPN access
- Data Loss Prevention (DLP): Monitor and prevent unauthorized data exfiltration
- Advanced Threat Protection: Deploy AI-driven threat detection systems
- Backup and Recovery: Maintain regular, tested backups isolated from the network
- Cyber Insurance: Transfer some financial risk while maintaining security standards
The Cost of Inaction
The Mino Kogyo incident illustrates that the cost of inadequate VPN security far exceeds the investment required to secure it properly. The company now faces:
- Complete VPN infrastructure shutdown with no reopening timeline
- Approximately 300GB of stolen data potentially exposed on the dark web
- Regulatory reporting obligations and potential penalties
- Forensic investigation costs
- System restoration and security enhancement expenses
- Immeasurable reputational damage and customer trust erosion
Conclusion
The ransomware attack on Mino Kogyo provides a clear lesson: VPN security cannot be an afterthought. As the primary gateway to corporate networks, VPNs represent both the most critical asset and the most vulnerable attack surface in modern enterprises.
The attack sequence—from initial VPN compromise to full system compromise in just one hour—demonstrates that traditional security approaches are insufficient. Organizations must prioritize VPN security through comprehensive measures including mandatory MFA, Zero Trust architecture, continuous monitoring, and rigorous access controls.
In Mino Kogyo’s case, the attackers needed only stolen credentials to initiate a catastrophic breach. For enterprises worldwide, the question is not whether VPN security should be a priority, but whether they can afford the consequences of treating it as anything less than the top priority it deserves.
The time to act is before the attack, not after. As Mino Kogyo stated in their disclosure, they hope that by sharing their experience, other organizations can avoid similar fates. The blueprint for prevention exists—it requires only the commitment to implement it before becoming the next cautionary tale.
